Accountable Care Organization (ACO)
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Top 30 ACO’s

In today’s changing healthcare environment, provider organizations face intensifying pressure to reduce costs and improve quality of care. To make progress on these divergent goals, healthcare provider organizations, including hospitals and health systems, are developing new ways of integrating with physicians and other clinicians for delivering care to patients. Also many provider organizations are currently exploring the benefits of transitioning to an accountable care enterprise. An Accountable Care Organization (ACO) is the equivalent of a joint venture between physicians, medical groups, clinics, health systems, hospitals and, in many cases, insurance companies. They have come together voluntarily to give coordinated, high quality care to their patients, with the goal of creating efficiencies, reducing costs, decreasing errors, and improving safety.

Under ACOs, decision making is more centralized and controlled. ACOs have significant control over decisions related to formulary, treatments, health IT adoption, sales-rep access, drug sampling policies, new product uptake and more. With so much at stake, service providers must understand how to position themselves in the eyes of the ACOs. Each organization needs to define a unique operating model and structure to support their chosen accountable care strategy.

  • Medicare Shared Savings Programs (MSS Programs) are designated to coordinate care for Medicare fee-for-service beneficiaries.
  • Commercial ACOs are distinct from Medicare ACOs in that a commercial payer, rather than Medicare, is the entity providing the financial incentives for quality and cost performance to provider organizations.
  • Look-Alike ACOs contract with commercial plans in a similar model to other ACOs but do not contract with Medicare.
  • Medicaid ACO is a fee for service through Medicaid. In fee-for-service Medicaid, reimbursement rates are set by the state, leaving no room for providers to raise prices. Also known as Accountable Care Collaborative.
  • Pioneer ACO is designed for early adopters of coordinated care that take on more risk than the MSS model

The number of physicians, nurse practitioners and physician assistants participating in ACOs exceeds 167,000. As of this writing, there are nearly 250,000 total healthcare providers and business personnel aligned with ACOs. These are the top 30 ACOs ranked in terms of total number of physician affiliations.


Corporation  Headquarters State Facilities Total Participating Physicians Type of ACO
1 Partners Healthcare  Boston MA 802 3,727 Pioneer
2 Valley Preferred Aetna  Allentown PA 490 3,533 Commercial
3 Hill Phys/Dignity Health/UCSF Health Net  San Ramon CA 1,138 3,279 Commercial
4 Heritage California ACO  Northridge CA 1,813 3,099 Pioneer
5 Hill Phys/Dignity Health CalPers ACO  San Ramon CA 1.139 3,081 Commercial
6 Indiana University Health ACO Inc.  Indianapolis IN 567 2,884 MSS Program
7 Hill Phys St. Mary’s Med Ctr Saint Francis Memorial Hospital & UCSF Med Ctr Blue Shield  San Francisco CA 979 2,843 Commercial
8 Cleveland Clinic Cigna ACO  Cleveland OH 372 2,743 Commercial
9 Baylor Quality Alliance  Dallas TX 536 2,376 MSS Program
10 Aurora Health Accountable Care Network Aetna  Milwaukee WI 367 2,188 Commercial
11 Montefiore Accountable Care Organization  Bronx NY 390 2,173 Pioneer
12 FamilyCare Inc.  Portland OR 804 2,091 Medicaid
13 Carolinas Healthcare System  Charlotte NC 479 2,075 Commercial
14 Mercy Clinic Mercy Hospital Springfield and Mercy Clinic Sprinfield  Chesterfield MO 492 2,009 MSS Program
15 Northwest Metro Alliance  Bloomington MN 212 1,891 Commercial
16 Advocate Physician Partners Accountable Care Inc.  Rolling Meadows IL 564 1,835 MSS Program
17 Heritage Provider Network & Blue Cross ACO  Northridge CA 1,380 1,825 Look-Alike
18 Renaissance Physician Organization  Houston TX 930 1,776 Pioneer
19 Banner Health Network  Mesa AZ 492 1,769 Pioneer
20 Iowa Health Accountable Care LC  West Des Moines IA 402 1, 682 MSS Program
21 Brown & Toland Physicians ACO  San Francisco CA 520 1,665 Pioneer
22 Penn Medicine & Independence Blue Cross  Philadelphia PA 311 1,614 Commercial
23 Valley Preferred Cigna  Allentown PA 353 1,590 Commercial
24 Trinity Pioneer ACO  Fort Dodge IA 420 1,565 Pioneer
25 Brown & Toland Physicians Cigna  San Francisco CA 383 1,542 Commercial
26 Brown & Toland Physicians Blue Shield  San Francisco CA 383 1,542 Commercial
27 OneCare Vermont ACO LLC  Colchester VT 362 1,540 MSS Program
28 Bon Secours Good Helpcare LLC  Marriottsville MD 461 1,531 MSS Program
29 University of Michigan Health System  Ann Arbor MI 208 1,503 MSS Program
30 University Hospitals Cigna  Shaker Heights OH 327 1500



Healthcare is transforming and ACOs are dramatically expanding. Under ACOs, decision making is more centralized and controlled. Understanding the influence and linkages of ACOs will help industry stakeholders better visualize and address the quickly changing landscape of coordinated care.